1. Field of the Invention
The present invention relates to a percutaneous absorption system and a percutaneous absorption method, and more particularly to a percutaneous absorption system and a percutaneous absorption method which enable an easy and continuous percutaneous absorption of medicine even when the medicine is formed of an oligomer or a high-molecular compound which are not generally suitable for percutaneous absorption.
2. Description of the Related Art
As an administration method of medicine in a situation where an immediate effectivity is desired, an injection is a typical example. Further, recently, a non-needle injection method adopting a jet injector which feeds medicine (medicine in a liquid form) in a human or animal body by making use of water pressure has been developed and has been served for clinical applications such as a subcutaneous injection of insulin.
However, when the injection or the jet injector is used, the medicine is temporarily injected into the body and hence, to sustain the medicine efficacy continuously, there has been a drawback that the administration must be performed frequently.
Further, as a sustainable or continuous medicine administration method, there have been proposed various types of percutaneous absorption systems including a percutaneous absorption system which is comprised of a reservoir for medicine (medicine in a liquid form) and an adhesive layer and a percutaneous absorption system which is comprised of a reservoir for medicine, a delivery control film which controls a delivery quantity of medicine and an adhesive layer.
For example, in JP7-255845A, there is disclosed a medicine administration method which uses a jet injector. To explain the method more specifically, as shown in FIG. 19, this publication discloses a percutaneous absorption system 100 which includes a jet injector 102 for forming a hole in a stratum corneum of skin by making use of water pressure, a reservoir 112 for storing medicine 106, a medicine-permeable adhesive layer 110 for closing an opening portion formed by the jet injector 102, wherein a rubber member 104 for closing an opening portion formed by the jet injector 102 is provided to a ceiling portion of the reservoir 112. The publication also discloses a method for promoting the percutaneous absorption of medicine using the percutaneous absorption system 100.
In such a percutaneous absorption system 100, the opening is formed in a surface of skin (not shown in the drawing) by way of the reservoir 112 and the adhesive layer 110 using the jet injector 102 and the medicine is percutaneously absorbed in the body through the opening portion by making use of the difference in concentration between the medicine in the reservoir 112 and the medicine in a blood vessel.
Further, in the JP11-509123A, as shown in FIG. 20, there is disclosed a percutaneous absorption system for delivering medicine. The percutaneous absorption system includes a reservoir 210 for storing active substance 208, which constitutes the medicine and a large number of micro-pins 206 or micro-blades for administrating the active substance, wherein openings 204 are formed in distal end portions of the micro-pins 206 or the micro-blades.
In such a percutaneous absorption system, a large number of micro-pins 206 or micro-blades formed on a bottom face of the reservoir 210 are pushed into a stratum corneum of a skin and, basically by making use of the diffusion of medicine attributed to the difference in concentration between the medicine in the reservoir 210 and the medicine in the blood vessel, the active substance 208 which constitutes the medicine is percutaneously absorbed in a human body or an animal body by way of openings 204 formed in the distal end portions of a large number of micro-pins or the like.
However, according to the percutaneous absorption system 100 and the percutaneous absorption promoting method of medicine using the percutaneous absorption system 100 disclosed in JP7-255845A, although the hole is formed in the stratum corneum of the skin surface, since the diffusion of medicine is performed basically by making use of the difference in concentration of medicine, there is a case that a penetration quantity of medicine is in short or insufficient. Particularly, when the medicine is formed of an oligomer or a high-molecular compound, it may be difficult to achieve the rapid penetration of medicine.
Further, according to the percutaneous absorption system 200 disclosed in JP11-509123A, the movement of the medicine 208 is performed only by the difference in concentration. Accordingly, although there may arise no serious problem in the movement of the medicine when the medicine is a low-molecular compound having a polarity, when the medicine is formed of an oligomer or the high molecular compound, it has been difficult to achieve the percutaneous absorption of the medicine.
Further, when a large number of micro-pins 206 or the micro-blades are pushed into a skin, the opening portions 204 formed in the distal end portions thereof are clogged and hence, it has been difficult to deliver the medicine 208 at a fixed rate.
Still further, since it is necessary to provide a large number of micro-pins 206 or micro-blades, it may be difficult to manufacture the percutaneous absorption system 200 and a length of the micro-pins 206 or the like is restricted so that the medicine cannot be delivered to the inside of the stratum corneum.
Additionally, according to a preferred embodiment of the percutaneous absorption system 200 disclosed in JP11-509123A, the introduction of a pump or a piezoelectric film into the system of the percutaneous absorption system 200 is proposed. In this case, however, there arises a new problem that the percutaneous absorption system becomes large-sized and hence, the portability and the economical aspect are deteriorated.
In view of the above circumstances, to solve the above-mentioned drawbacks, the inventors of the present invention have extensively studied the problems and have made a following finding as a result of the study. That is, by applying pressure to medicine by way of a medicine holding portion and by breaking a substrate using a mechanical stimulus such as an injection needle or the like, it is possible to provide a percutaneous absorption system which exhibits the excellent portability and the excellent adhesiveness while enabling the continuous and rapid percutaneous absorption of medicine with respect to a largely different types of medicines. The present invention is completed based on such a finding.
That is, it is an object of the present invention to provide a percutaneous absorption system, which has a simple structure and enables an easy and continuous percutaneous absorption of medicine even when the medicine is formed of an oligomer or a high-molecular compound and a percutaneous absorption method, which uses such a percutaneous absorption system.